Tool for making electrical connections



1945- v. E. CARLSON TOOL FOR MAKING ELECTRICAL CONNECTIONS Filed June29, 1943 9 "1 ATTRNEY Patented Aug. 14, 1945 TOOL FOR MAKING ELECTRICALCONNECTIONS Vernon E. Carlson, Cranford, N. J., assignor toAircraft-Marine Products,

Inc., Elizabeth,

W. 1.. a corporation of New Jersey Application June 29, 1943, Serial No.492,695

4 Claims. (01. 140-113) This invention relates to means for makingelectrical and mechanical connections and more particularly to a tool ofthe pliers type provided with a plurality of die surfaces of graduatedsizes for use in crimping a variety of sizes of ferrules,

especially for application of electrical connectors onto appropriateelectrical conductors.

In recent years electrical connectors of the solderless type haveenjoyed outstanding success. Most such connectors consist of a terminalcontact portion to engage the electric terminal or binding post and asleeve-like ferrule portion for receiving the end of an electricalconductor. In use, the ferrule of the connector is telesooped over theend of the wire of a conductor, and a superior bond is effected betweenthe connector and the conductor by appropriately crimping the ferruleportion of the connector directly onto the wire of the conductor. Theconnection thus formed not only may be made to meet full strengthrequirements but also, by virtue of the intimate pressure contactbetween the surfaces. can be made to have less electrical resistancethan any practical connection heretofore known. Various apparatus forcrimping connectors onto conductors have been devised, among the moresatisfactory being tools of the types described and claimed in thecopending applications of U.

A. Whitaker and Vernon E. Carlson, Serial Nos.

455,039 and 455,033, respectively, filed August 17, i

1942; and of Stephen N. Buchanan, Serial No. 474,935, filed February 6,1943.

It is an object of the present invention to provide a practical tool forforming crimped connections between electrical connectors and electricalconductors, whereby an assortment of different sizes of connectors maybe secured to appropriate conductors. Other objects will be in partpointed out as the description proceeds and will in part become apparenttherefrom.

In the aforementioned application of U. A. Whitaker a satisfactory toolis disclosed and claimed for attaching connectors falling within arather limited range of sizes to electrical conductors. It has beendiscovered that a plurality 'of dies of the general type illustratedin'his application may be combined in a single tool having acorrespondingly greater range of applications if the complementary diesare arranged as hereinafter set forth and if special precautions aretaken to prevent the ferrules of the connectors from being squeezed orcammed laterallyout of the bite of the proper dies as the jaws areclosed.

Notwithstanding that the laws open wider at their outer ends, so that ithas beennatural to arrange the largest holes at this end, I use thereverse arrangement, and thereby obtain the greatest mechanicaladvantage close to the pivot axis for the jaws. The smaller dies arearranged. correspondingly further from the pivot axis; and thus with anormal hand pressure applied to the tool a proper crimping force isapplied to whichever ferrule is engaged in its appropriate dieopening.This concept, however, is not a wholly satisfactory solution of theproblem. In order to use this reversed arrangement so as to crimp thelargest ferrules between dies located closest to the pivot axis of thejaws, it is necessary that the jaws be opened to an abnormally wideangle in order to separate the die surfaces sufilciently to insert theferrule, and unless special precau tions are taken, the ferrule is notproperly engaged upon closing of the laws, but instead is squeezed orcammed out of the die, so as to escape entirely from the ,bite of thedies or'at best to produce an objectionably lop-sided crimp.

The present invention includes the discovery that flat, relativelynarrow die areas placed on each side of the concave dies which do themain part of the crimping may advantageously be used to bite into theferrule and to prevent it from being displaced laterally with respect tothe pivot point about which the jawsclose. These flat dies flank, andintersect with, the concave dies to form a sharp edge between eachconcave surface and each fiat surface. It has. been discovered thatbetween these sharp edges and flat flanking tion even though theoperation is carried out quite near the pivot point about which the jawsclose, and by keeping the flanking surfaces narrow, the coining areas ofthe dies are reduced and hence less crimping pressure is required.

In this specification and the accompanying drawing, I have shown anddescribed a preferred embodiment of my invention; but it is to beunderstood that this is not intended to be exhaustive nor limiting ofthe invention, but on the contrary is given for purposes of illustrationin order that others skilled in the art may fully understand theinvention and the principles thereof and the-manner of applying it inpractical use so that they may modify and adapt it'in various forms,each as may be best suited to the conditions of a particular use.

In the accompanying drawing, in which an exemplary embodiment of theinvention for J including a plurality of progressively sized dies,formed in accordance with the invention;

Figure 2 is a sectional view through the jaws of the hand toolillustrated in Figure 1, butshow ing the jaws closed upon and crimpingtogether an electrical connector and conductor; and Figure 3 is aperspective view of the electrical connector and conductor as crimpedtogether in Figure 2.

With reference to Figure l, a tool is shown consisting of a pair of handlevers 20 and 2| pinned together by a pin 24 and pinned respectively toan, upper jaw member 26 and a lower jaw member '21, by an upper jaw pin28 and a lower jaw pin 29. Jaws 26 and 21 are linked together with alink 30 by means of an upper link pin 32 and lower link pin 33. Betweenthe jaw members a, bearing pivot pin 34 is positioned. -Hence, whenlevers 20 and 2| are brought toward one another, jaw pins 28 and 29,being located on the other side of pin 24 from the hand portions oflevers 20 and 2|, are separated, and jaw members 26 and 21 are rotatedabout link pins 32 and 33 with a rocking motion upon pivot pin 34 toclose the free ends of the jaw members with a greatly multiplied force.

Jaw member 26 is provided with three concave die surfaces 40, 42 and 44,and jaw member 21 is correspondingly provided with three cooperatingconcave die surfaces 4|, 43 and 45', respectively. Die surfaces 40 and4| are larger than die surfaces 42 and 43, and die surfaces 42 and 43are larger than die surfaces 44 and 45. Jaw member 25 is also providedwith flat, relatively narrow die surfaces 50, 52, 54 and 56 which flankthe various concave die surfaces 40, 42 and 44. correspondingly, lowerjaw member 21 is provided with fiat, relatively narrow die surfaces 53,55 and 51 flanking the lower concave die surfaces 4|, 43 and 45; Thefree ends of the jaws are provided with stops 50 and 5| to limit theextent to which the jaw members may be closed.

As shown in Figure 1, each side of the jaw portions of members 26 and 21is beveled from adjacent pivot pin 34 to the free ends thereof, andthese bevels increase in extent from the pivot pin toward the free endsof the jaws. Thus, fiat die surfaces 50 and 5| are broader, in adirection across the face of the jaws, than surfaces 56 and 51. And theintermediate die surfaces likewise vary in breadth accordingly, frombroader toward pivot pin 34 to narrower toward stops 60 and 6|. Hence,the bevel configurations of the tool combine with the depth of the die Isurfaces to give broader die surfaces where the larger ferrules are tobe crimped and narrower die surfaces where the smaller ferrules are tobe crimped. In this manner the proportions of each die and of eachresulting crimp are maintained at an optimum for every ferrule, and atthe same time the mechanical advantage varies so as to give the greaterforce required for the larger crimping areas and heavier ferrules, allby a simple series of dies of different sizes feasibly combined in asingle, multirange-tool.

Figure 2 shows jaws 26 and 21 closed upon an electrical conductor havinga bared wire end 1| positioned in an electrical connector consisting ofa terminal contact portion 12 and a ferrule portion 13. The cooperatingdie surfaces 42 and 43 are shown impressing a double crimp into ferrule13 of the connector. This double crimp is further described in theabove-mentioned application of U. A. Whitaker. When ferrule 13 ispositioned, for example, between die surfaces 42 and 43 and the dies areclosed together, however, the sharp edges above (see Figure 1) betweendie surfaces 52 and 42, and 42 and 54, and below between die surfaces 53and 43, and 43 and 55, along with the flanking, fiat die surfaces, serveto engage and support the ferrule; and in the finished crimpedconnector, as illustrated in Figure 3, narrow fiat crimped areas 15 areformed by fiat die surfaces 54, and convex'crimped areas 14 are formedby concave die surfaces 42.

The particular pair of main concave die surfaces to be used in a givencrimping operation is selected in accordance with the size of theferrule to be crimped, and ordinarily the preferred relationshipconsists of selecting concave dies having a chordal width approximatelyequal to the inner diameter of the particular ferrule, as described andclaimed more fully in said copending application of Stephen N. Buchanan,Serial No. 474,935, filed February 6, 1943.

The invention has been described in connection with one type of handtool. Obviously other types might equally well incorporate theinvention. And it might be incorporated in a pedaloperated orpower-operated die press. The discovery is a thoroughly practical oneand may be applied wherever a series of sizes of die surfaces aredesired in a multisize tool. Moreover, certain features of my inventionmay be used wherever two dies approach one another angularly, as about apivot axis, and in general wherever there is a tendency for the workbetween the dies to move outwardly from the pivot point as the jawsclose.

As various embodiments may be made of the above invention and as changesmight be made in the embodiment above set forth, it is to be understoodthat all matter hereinbefore set forth or shown in the accompanyingdrawing is to be interpreted as illustrative and not in "alimitingsense.

I claim: a

1. In apparatus of the character described and including a pair of diesclosable toward one another, a series of concave crimping surfaces ineach die; each die being beveled in the direction I toward the face ofthe die that engages the work,

said concave crimping surfaces being cut into the beveled faces of thedies and ranging through a progression of sizes and depths, and saidbeveling being progressively greater toward the ends of the dies wherethe concave crimping surfaces are smallest and shallowest.

2. The invention of claim 1 wherein adjacent concave crimping surfacesare separated by narrow flat die surfaces.

3. A tool adapted to crimp a plurality of sizes of electrical connectorsonto electrical conductors and including, a pairof jaws closable towardone another in pliers fashion about a pivot point, and multiple diesurfaces in the jaws extending in each from a point adjacent the pivotpoint to a point adjacent the free end of each jaw; said multiple diesurfaces including a series of concave ferrule-crimping surfaces rangingin sizes progressively with the largest located nearest the pivot pointand the. smallest located nearest the free ends of the jaws, whereby thegreatest force multiplication is available for the largest'ferrulescrimped; said die surfaces for crimping a given ferrule includingopposing concave die portions in the upper and lower jaws of a widthapproximately equal to the inner diameter of the ferrule to be crimped,and narrow float dies portions I aaaaaee v multiple die surfacesincluding a series of con cave ferrule-crimping surfaces ranging insizes progressively with the largest located nearest the flanking eachside of the concave portions, whereby, as the jaws close upon theferrule, the die edges formed by the intersections of the concaveportions withthe flat portions tend to dig into and hold the ferrule andthe narrow flanking flat portions engage and fold diametrically locatededges of the ferrule being crimped to reduce the tendency of the ferruletoward lateral displacement or spreading as the concave die portionscrimp the central areas of the ferrule into the electrical conductor.

4. A tool adapted to crimp a plurality of sizes of electrical connectorsonto electrical conductors and including, a pair of jaws closable towardone another in pliers fashion about a pivot point, and multiple diesurfaces in the jaws extending in each from a point adjacent the pivotpoint to a point adjacent the free end of each jaw; said pivot point andthe smallest located nearest the free ends of the jaws. whereby thegreatest force multiplication is available for the largest ferrulescrimped; the die-carrying portions of the jaw members being beveled inthe direction in which each jaw closes, whereby the deeper cut dieouriaces are correspondingly broader than the ahallower die surfaces.and the bevel of each jaw being progressively deeper in a direction fromthe pivot point toward the free end of the jaw. whereby the die surfacestoward-the free ends of each jaw are correspondingly narrower than thedie VERNON E. canteen.

